Mutual Defense Agreement (1958)

E6872

Cold War treaty bilateral defense treaty international agreement

The Mutual Defense Agreement (1958) is a landmark Cold War-era treaty that deepened U.S.–UK strategic cooperation by enabling extensive collaboration on nuclear weapons and defense technology.

Aliases (3)

Statements (50)

Predicate	Object
instanceOf	Cold War treaty → bilateral defense treaty → international agreement →
aimsTo	strengthen Western nuclear deterrence against the Soviet Union →
category	Nuclear weapons policy of the United Kingdom → Nuclear weapons policy of the United States → United States–United Kingdom military relations →
compliesWith	United States non-proliferation obligations as interpreted by the US government →
countryParty	United Kingdom of Great Britain and Northern Ireland → United States of America →
enables	cooperation on nuclear submarine propulsion technology → cooperation on nuclear warhead safety and reliability → joint work on nuclear weapons effects and testing data → transfer of nuclear weapons-related design information from the US to the UK →
enteredIntoForceDate	1958-08-04 →
enteredIntoForceYear	1958 →
era	Cold War →
field	atomic energy → defense technology → nuclear weapons →
geopoliticalSignificance	key instrument in NATO’s overall nuclear posture → symbol of the special relationship between the United States and the United Kingdom →
influencedBy	strategic competition with the Soviet Union →
language	English →
legalBasis	United States Atomic Energy Act of 1954 as amended →
officialName	Agreement between the Government of the United States of America and the Government of the United Kingdom of Great Britain and Northern Ireland for Cooperation on the Uses of Atomic Energy for Mutual Defence Purposes →
purpose	to deepen US–UK strategic cooperation on nuclear weapons and related technology → to enable cooperation on the uses of atomic energy for mutual defence purposes → to enhance joint nuclear deterrence capabilities of the US and UK → to facilitate cooperation on nuclear propulsion for naval vessels → to facilitate exchange of classified information on nuclear weapons design and manufacture →
relation	complements the 1963 Polaris Sales Agreement → forms the legal framework for much of the US–UK nuclear relationship → supports the UK’s independent nuclear deterrent through US technical assistance →
renewal	extended multiple times since 1958 → periodically renewed by both governments →
renewalInterval	typically 10 years →
restriction	cooperation limited to mutual defence purposes → does not authorize transfer of complete nuclear weapons →
shortName	US–UK MDA → US–UK Mutual Defence Agreement →
signingDate	1958-07-03 →
signingYear	1958 →
status	in force →
subjectTo	periodic review by the UK Parliament → periodic review by the US Congress →
typeOfCooperation	collaboration on nuclear materials handling and safety → collaboration on nuclear weapons delivery systems-related technology → exchange of classified nuclear information → technical assistance on nuclear warhead design →

Referenced by (6)

Subject (surface form when different)	Predicate
Agreement between the Government of the United States of America and the Government of the United Kingdom of Great Britain and Northern Ireland for Cooperation on the Uses of Atomic Energy for Mutual Defence Purposes → Mutual Defense Agreement (1958) ("US–UK Mutual Defence Agreement") → US–UK MDA ("US–UK Mutual Defence Agreement") →	shortName
Agreement between the Government of the United States of America and the Government of the United Kingdom of Great Britain and Northern Ireland for Cooperation on the Uses of Atomic Energy for Mutual Defence Purposes ("US–UK Mutual Defense Agreement") → Agreement between the Government of the United States of America and the Government of the United Kingdom of Great Britain and Northern Ireland for Cooperation on the Uses of Atomic Energy for Mutual Defence Purposes ("1958 Mutual Defense Agreement") →	alsoKnownAs
Anglo-American relations →	includesAgreement